The year 2026 could be marked by new global alerts related to viruses that could be considered emerging. Experts point out that, since the Covid-19 pandemic, a combination of risk factors has created favorable conditions for the evolution and spread of infectious agents, at a pace considered accelerated.
Among the main factors are: global warming, population growth and increased human mobility, elements that increase contact between people, animals and previously isolated environments, facilitating the emergence and spread of new viruses.
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An article published in The Conversation magazine, written by Patrick Jackson, associate professor of Infectious Diseases at the University of Virginia, in the United States, highlights three viruses that deserve special attention in 2026: H5N1 bird fluo mpox and the still little known Oropouche virus.
According to the publication, the objective is to anticipate strategic surveillance actions in the face of the threat of these viruses, which have recently expanded their circulation area and started to worry health authorities in different regions of the world.
Based on this warning, the Paraíba newspaper Below is a list of the viruses identified in the study and explains why they are on the international public health radar.
Oropouche Virus
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First identified in 1950, the Oropouche virus is transmitted by mosquitoes and causes flu-like symptoms. Considered restricted to the Amazon for decades, the virus now represents a growing threat in Brazil and other countries in the Americas.
Since the 2000s, Oropouche has been expanding to areas of South America, Central America and the Caribbean, a movement associated with the adaptation of the main vector to increasingly larger and urbanized environments.
The scenario worsened from 2023 onwards, when the circulation of the virus began to gain strength again in Brazil. Data from the Pan American Health Organization indicate that, until August 2025, the country concentrated 90% of cases registered in the Americas, with the disease occurring in 20 states. During the peak period, five deaths were confirmed, four in Rio de Janeiro and one in Espírito Santo.
To date, there is no preventive vaccine or specific treatment for Oropouche, which increases the risks in case of infection and raises awareness among health authorities.
Faced with this scenario, on January 5, 2026, the World Health Organization (WHO) presented a proposal to accelerate the development of prevention and control tools against the virus, reinforcing the need for international surveillance and coordinated response.
H5N1 bird flu
Influenza A has historically been treated as a threat to public health due to its high capacity for mutation. Over time, the disease has caused pandemics, the most recent being in 2009, caused by the H1N1 strain, which resulted in more than 280,000 deaths in the first year, according to international estimates.
Currently, experts’ biggest concern is related to the H5N1 strain, responsible for the so-called bird flu. Previously associated almost exclusively with birds, the circulation of the virus became even more worrying after the identification, in 2024, of infections in dairy cows in the United States, indicating a broadening of the host spectrum.
In Brazil, a case of bird flu was confirmed in 2025 on a commercial farm. The main fear of health authorities is that the virus will be able to adapt to transmission between humans, a hypothesis that, to date, has not been confirmed.
Data from the Centers for Disease Control and Prevention (CDC) indicate that, since 2024, 71 human cases of the disease and two deaths have been recorded, with no evidence of sustained community transmission.
Given the potential risk, specific vaccines against the H5N1 strain are already under development, as currently available formulations do not offer adequate protection. In Brazil, the Butantan Institute is conducting pre-clinical safety studies for a vaccine targeting the new strain, as part of preparedness strategies for a possible health emergency.
Mpox
Considered a rare disease for decades, mpox circulation was practically restricted to specific regions of Africa for a long time. This scenario changed in 2022, when the strain clade IIb It spread quickly and was registered in more than 100 countries.
Transmission of the virus occurs mainly through close physical contact, often associated with sexual intercourse. Since 2024, health authorities have observed a significant increase in cases in Central Africa, a region that also began to confirm infections with the strain clade Iconsidered more serious.
Currently, there is a vaccine available against mpox, but there is no defined specific treatment for the disease. Experts estimate that the evolution of the virus and its ability to adapt could impose new challenges to public health throughout 2026.
In addition to the three viruses identified as priorities by experts, other diseases could also pose challenges to public health in 2026. Among them is chikungunya, which has returned to significant numbers in recent years.
According to the magazine IFL Science, throughout 2025 the disease recorded more than 445 thousand suspected cases worldwide, in addition to 155 deaths until the month of September. In Brazil, data from the Ministry of Health shows 129 thousand cases and 121 deaths in the same period.
Measles also once again worried health authorities in different countries.
Experts also warn of the possibility of HIV advancing in the coming years if cuts persist in international health cooperation programs, which are essential for the prevention, diagnosis and treatment of the infection in low- and middle-income countries.
*With information from g1
